The major nutritive portion of the ruminants diet consists primarily of polysaccharides such as cellulose and starches. These primary sources of said animals energy requirements, and of basic intermediates for tissue building processes, are hydrolized in said animals rumen by microbiological processes to monosaccharides, primarily to glucose. The thus formed glucose is then further degraded by enzymatic processes to pyruvic acid and derivatives thereof. These in turn are further converted through various enzymatic processes to acetic acid and propionic acid and derivatives thereof. Simultaneously, and also in the rumen, some of the acetic acid is converted to butyric acid. Although butyric acid is the component most efficiently metabolized by ruminants while acetic acid is the least efficiently utilized product of the above referred-to digestive processes, the formation of butyric acid in the course of said microbiological processes is energetically not very favorable. As stated above, butyric acid is formed from acetic acid, and since one mole of glucose yields two moles of acetic acid and two moles of methane and/or carbon dioxide gas, and since two moles of acetic acid are consumed in the formation of one mole of butyric acid, therefore, for every mole of butyric acid formed, two moles of methane and/or carbon dioxide gas are generated, representing a considerable energy loss. Additionally, it is known that production of acetic acid (and/or acetates) in larger than normal amounts may lead to the production of ketone bodies (acetoacetate, acetone and .beta.-hydroxy butyrate) which can cause ketosis in ruminants, especially if said animals are under stress. It has been found that the supplementary feeding of propionic acid (and/or propionates) is beneficial for minimizing the effects of ketosis. A further advantage of feeding a diet high in propionic acid to ruminants such as cattle, sheep and goats is to lower the incidence of ketosis.
Thus it would be of advantage both to the animal grower and feedlot operator if the microbiological processes of the rumen could be altered so that the production of propionic acid from carbohydrates is enhanced while that of acetic acid is suppressed.